1. Field of the Invention
The invention relates to a measuring transformer for use with high-voltage switch-gear of a type employing metal encapsulation and, in particular, to a measuring transformer which is retained between flanges at a joint of the metal encapsulation of the switch-gear.
2. Description of the Prior Art
In one known measuring transformer of the afore-mentioned type ("PTB-Mitteilungen," 1/73, page 38), cores with secondary windings are assembled on a cylindrical aluminum part which has two flanges. One flange serves to fasten another flange part, which part engages over the cores having the secondary windings, while the other flange of the cylindrical aluminum part connects with a flange of the metal encapsulation at a joint thereof. By means of another flange, the over engaging part is assembled to another flange of the metal encapsulation so that the transformer, formed by the two parts, with the iron cores including secondary windings housed between them, is retained at a joint between the flanges of the metal encapsulation.
The aforesaid design of the known measuring transformer is relatively complicated because it employs a first cylindrical aluminum casting as support for the iron cores having the secondary windings and another casting to cover up such cores. As a result, the transformer is relatively expensive to manufacture.
It has also been proposed (German patent application No. P 23 25 441.3) to employ for the assembly of a measuring transformer within a metal capsule of a switch-gear installation an annular mounting attachment which is attached to the measuring transformer and clamped between the flanges of the metal capsule. In such a transformer, however, the active-system thereof comprising the iron cores and secondary windings is disposed entirely inside the metal capsule.
It is an object of the present invention to provide a measuring transformer for use with high-voltage switch-gear which is of a simple design and, thus, can be manufactured at low cost.